Construction of molds



June e, 1939. H, E, MCWANE 2,161,522

Y CONSTRUCTION OF MOLDS Original Filed Oct. l2, 1934 Patented June 6, 1939 UNITED STATES PAT EN OFFICE Application October 12, 1934, Serial No. 748,124v

Renewed-December 11, 1937 7 Claims. (01122-165)V This invention relates to, and more particularly has reference to a mold and core structure.-

As is well known, a casting during cooling shrinks considerably from its initial size when originally poured. This presents certain difculties under all circumstanecs, inasmuch as there are set up in the metal various stresses and strains. 'I'hese are particularly objectionable, however, in casting operations in which permanent cores are employed, inasmuch as such cores prevent the free shrinkage of the casting, thereby increasing the stresses and strains; if notl actually causing cracks and other imperfections in the casting.

Various endeavors-have been made to overcome these diiculties, but a satisfactory solutionV has not up to this time been obtained. In general, the prior suggestions have centered principally around the use of sand cores or other destructible cores which are capable of limitedmovement during the shrinkageof the casting.- I have in mind particularly cores which are used for the formation of bolt holes or other types-of apertures or recesses in cast articles, and with-respect to these it has heretofore been necessary to manually arrange the cores in the mold cavities prior to each pouring operation. This, together with the fact that aA new core must be made up and usedk for each pouring, constitutes an appreciable item in the cost of casing. The manual positioning of the cores also is unsatisfactory, inasmuch asY there is of course always the possibility of an operator misplacing the core and thereby rendering the casting Worthless.

To overcome the above disadvantages is one of the objects of my invention.

Another object of my invention is to provide a permanent core which permits of the free shrinkage of a casting.

Yet another object of my invention is to provide a core that is self-setting.

To accomplish the above and other important objects, as will more fully appear hereinafter, my invention in generalcontemplates the use of a core which is adapted to be normally4 positioned at its desired location in a mold cavity, but which may be displaced therefrom upon shrinking of the casting, and which is adapted to return to its normal position upon removal of thecasting from the mold cavity.

In order to insure a more adequate comprehension of my invention, reference is made to the accompanying drawing, in which one specic embodiment of my invention is depicted, it

being of course understood that various other forms may beresorted to in order' to practicethe invention, and that I am to be bound vsolely by the: scope of the appended .claimsi .In the drawing, in which corresponding numerals refer to the same parts;

Figure 1 is a top plan View of the lower half ofafmold and cores-constructed in accordance with my invention.

Figure 2 is a sectional view taken along the line 2 2, of-Figure 1, and also show-ing the top half of the mold in-assembledV position Figure 311s a plan view looking along the line 3 3 of-Figure'2.

Figure 4 is a Viewsimilar-to Figure.v 2, but showing a modified-form of` core.

Figure 5 is adetailed top -plan View of the core shown in Figure 4.

Figure -6 is a vertical-sectional viewshowing a casting in the mold cavity and disclosing the manner of operation ofthe cores.l

Figure 7 is a View of a bolt for usev with`a casting of the-type made` in molds-such as vshown i-n Figures 1, 2 and.

Figure 8 is a view-of a bolt for use with castings made inA a mold such as shown in lFigures 4 and 5.

While my invention is adapted for-use in makingcastings of various-types and designs, I will specically illustrate it in connection With a casting of relatively flat shape in-which it is desiredto provide bolt holes or other-vtypes-of vapertures or recesses.

In Figure `-l there is disclosed the lower half l of a mold which, for thepurposes of illustration, is designed for thev casting of plow plates. I have shown thismold as beingY provided with two mold cavities -2` communicating with individual gates -3 and amain gate 4. Suitable risers 5 may be provided as necessary.

Myinvention relates to the cores, designated generally as (il, whichl are shown positioned at the desired places in the mold caVitiesZ. yReferring to Figure 2, it will Abe noted that thefcore is of frusto-conical shape having slanting walls 'l and a at top 8. As will be noted from Figure 2, theto'p 8- is-adapted to bear against the` upper half 9 of the mold and the core. extendsthroughout the depth of the mold cavity. Therefore,

vwhen themetal is poured it will ow around the core, thus leaving an aperture in the finished casting, as will be later described.

Asbest shown in .Y Figure 3, a rib `Il maybe formed the length of the core, thereby providing a groove in the; aperture of the casting which.

is adapted to receive a rib I2 formed on the bolt I3 which is used in connection with the casting. The provision of this rib on the bolt head and the groove in the aperture of course prevents rotation of the bolt when a nut is enthreaded thereon.

There is drilled into the base of the mold a channel which is preferably cylindrical for a portion of its length, as indicated at I4. This channel extends to the mold cavity in the form f a taper, as indicated at I5. For use with a core such as shown in Figure 2, this taper is of frusto-conical shape and has an angle of taper that is the same as the angle of taper on the core 1. A channel I6 is cut into the tapered wall I5 for the purpose of receiving the rib Il on the core, and this provision serves as a guide for the core.

While the angles of taper of the core I and channel I are the same, the relative sizes of the core and tapered channel are such that the channel prevents the extension of the core beyond that point at which its upper surface 8 contacts the top of the mold 9. At this position the core iits snugly within the taper I5, thereby preventing the leakage of any molten metal from the core cavity. It will also be noted that the tapered wall I5 is continued for a suiicient distance to permit the top 8 of the core to lie flush with the base of the cavity 2.

On the base of the core I provide a stub I'I which serves as a guide in setting one end of a coil spring I8 upon the core. The lower end of the spring is seated over a stub I9 mounted on the inside of a screw 2l which is enthreaded into the chanel I4. A suitable recess 22 is provided for the purpose of affording a grip for any suitable instrument to rotate the screw.

The operation of my device is apparent from the foregoing. During the initial construction of the mold, the core E is inserted in the channel I4 and extended to the upper and conical section I5 of the channel At this time the core is rotated until its rib II lies Within the channel I6 of the tapered section. The spring I8 is then seated over the knob II and the knob I9 of screw 2|. The screw is then screwed into the channel I4 to a degree to maintain the desired tension on spring I8. The core is thereby maintained at its maximum extended position from the channel I5, which, as above stated, is such that the top 8 of the core will lie against the base of the top half 9 of the mold when the mold is assembled, at the same time presenting a tight t between the core and the tapered channel I5 to prevent the leakage of any molten metal from the mold cavity into the channels I5 and I4.

Before casting, the top half 9 of the mold is of course closed over the lower half I, and the mold locked in such assembled position. Molten metal is then poured into a suitable gate, such as that indicated by the numeral 4, and then passes into the mold cavity. The metal will flow all around the core, or cores, and completely ll the cavity. When the cavity is filled, the metal is allowed to cool. Upon solidication, the casting 24, shown in Figure 6, includes apertures such as 25, which of course correspond to the shape of the core. During cooling, the casting shrinks, and draws away from the Walls of the mold cavity, as shown at 26 in Figure 6. This results in a corresponding displacement of the apertures 25.

As is apparent, however, the core is capable of withdrawing within the tapered channel I5, and the imposition of a horizontal thrust upon the core results in such Withdrawal.

As best shown in Figure 6, the displacement of the apertures 25 results in the withdrawal of the core Within channel I5, and it is to be noted that at all times during such withdrawal, the tapering wall 'I of the core is in constant contact with the slanting channel I5. This maintains the axis o-f the core at all times perpendicular, which of course means that there is therefore no danger of the core scratching or chipping any of the casting adjacent the aperture 25.

Of course, as soon as the casting is removed from the mold cavity, the spring I8 returns the core to its uppermost position in chanel I5, ready for the next pouring operation. This return of the core in such position is not only automatic, thereby saving the expense of a manual setting of the core, but also insures that the core will be set at a uniform place over a series of pouring operations.

In Figures 4 and 5 I have shown a core similar in all respects to Figures 1 through 3, save only for the fact that the core is frusto-pyramidal in shape instead of frusto-conical. In this modification the core is provided with a top 8 similar to the top of the frusto-conical core. I have shown it provided with four flat sloping surface walls 21, 28, 29 and 3|. Of course, any number of walls may be employed in lieu of the number shown herein.

When employing a core such as that shown in Figures 4 and 5, it will of course be obvious that flat side Walls 32 will have to be substituted for the frusto-conical channel I5. The operation of this type of core is identical with that described above in connection with a frusto-conical corenamely, a withdrawal of the core into the converging channel upon shrinkage of the casting and a return of the core to its operative position upon removal of the casting from the mold cavity.

The core shown in Figures 4 and 5 is adapted for use with a bolt having a head 33 such as that set forth in Figure 8. In such a construction it is of course not necessary to provide a rib on the bolt head in order to prevent rotation. It will of course be appreciated that the ribs II and I2 o-f the core and bolt head 'I and I3, respectively, may be omitted when it is not essential to provide positive means to prevent rotation. As a matter of fact, the omission of such ribs is sometimes desirable, and it is to be noted that the omission of the rib II permits of somewhat greater freedom of movement of the core 6.

It is believed that the advantages of my invention are apparent. In addition to being economical in construction and maintenance, further economies are effected by obviating the manual setting of the core in the mold cavity and the prevention of losses through imperfect castings. Furthermore, the cores are always 'set at a uniform place in the mold cavity, thus insuring any number of castings having corresponding apertures.

While I have shown and described the preferred embodiment of my invention, I wish it to be understood that I do not conne myself to the precise details of construction herein set forth, by way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled in the art, without departing from the spirit of the invention, or exceeding the scope of the appended claims.

I claim:

1. In a casting mold, a tapered channel extending into the mold cavity, a core having an angle of taper corresponding to that of the channel, said core slidable in the tapered channel and adapted to extend into the mold cavity, and means to normally maintain the core in extended position but permitting its recession into the channel upon displacement of the core in the casting formed by the mold.

2. In combination with a casting mold, a core having a regularly tapered wall, a channel opening into the mold cavity and having a wall with ran angle of taper corresponding to the tapered core Wall, said core adapted to slidably t in the said channel and extend into the mold cavity, the relative sizes of the core and channel being such as to limit the extension of the core into the mold cavity, and resilient means to normally maintain the core in such extended position.

3. In combination with a casting mold, a frusto-conical core member, a channel opening into the mold cavity, such channel being of frustoconical shape and having an angle of taper corresponding to that of the core, said core adapted to slide in the channel and to extend from the channel into the mold cavity, and means to normally maintain the core in extended position but permitting its recession into the channel upon displacement of the hole in the casting formed by the core and to return the core to extended position upon removal of the casting from the mold cavity.

4. In combination with a casting mold, a frusto-pyramidal core member, a channel opening into the mold cavity, such channel being of frustofpyramidal shape and having an angle of taper corresponding to that of the core, said core adapted to slide in the channel and to extend from the channel into theA mold cavity, and means to normally maintain the core in extended position but permitting its recession into the channel upon displacement of the hole in the casting formed by the core and to return the core to extended position upon removal ofY the casting from the mold cavity.

5. In a casting mold, a tapered channel extending into the mold cavity, a core having a taper corresponding to that of the channel and adapted to'slide in the channel, the core having a rib which iits into a groove provided in the channel, and means located in said channel for Y normally maintaining the core in the mold cavity but permitting its recession into the channel upon displacement of the hole in the casting formed by the core.

6. In a casting mold, a tapered channel extending into the mold cavity, a core having a taper corresponding to that of the channel and adapted to slide in the channel, the core having a rib which fits into a groove provided in the channel, and spring means located in said channel for normally maintaining the core in the mold cavity but permitting its recession into the channel upon displacement of the hole in the casting formed by the core.

'7. In combination with a casting mold, a core having .a regularly tapered Wall, a channel opening into the mold cavity and having a wall with an angle of taper corresponding to the tapered core Wall, a rib on said core which ts into a groove provided in the channel, the core adapted to slidably fit in the channel and extend into the mold cavity, the relative sizes of the core and channel being such as to limit the extension of the core into the mold cavity and resilient means to maintain normally the core in such extended position.

HENRY E. MCWANE. 

